This invention relates to rotating machinery and more particularly to a shaft sensor for monitoring rotating machinery.
Monitoring and maintenance methods for rotating machinery, such as generators, motors and turbo-machinery, currently lack sufficiently reliable for accurately indicating certain important problems, such as cracking of power transmission components or their structural support members, inadequacy of local lubrication, excessive wear, shorted insulation, stator winding faults, and various other failures. Rotating machinery faults and failures lead to unnecessary expenses, which could be avoided by timely repair or scheduled maintenance. The occasional catastrophic failure of rotating machinery can result in costly repairs and system down-time, having a rippling effect on businesses dependent on the plant machinery or the power generated by the plant machinery. Downtime caused by a failure of rotating machinery reduces productivity and profitability.
Therefore, there is a need to monitor rotating machinery to reliably predict development of a failure as well as to determine when the rotating machinery operation is normal.
The present invention is a rotating machinery monitor, which provides a warning that is indicative of a developing problem with the rotating machinery. The rotating machinery monitor has at least one current sensor for detecting shaft grounding current in the rotating machinery, at least one voltage sensor for detecting shaft voltage in the rotating machinery, a change detector for determining rate of change in the shaft grounding current and a rate of change in the shaft voltage, and an evaluation system for producing a warning as a function of the change in the shaft grounding current, the rate of change in the shaft voltage, the shaft grounding current and the shaft voltage. A method for practicing the present invention is also described.